Session Modes

Session modes are the quick-switch surface for changing BMO’s prompt and runtime posture without editing config. Use them for fast context changes in the TUI. For stateful multi-phase workflows, use Choreography.

Built-in modes

/mode code     # full implementation mode
/mode chat     # read-only: no write/edit/bash
/mode coordinator # delegation-first lead mode
/mode review   # read-only: view, grep, glob + LSP
/mode debug    # subset with bash + diagnostics
/mode plan     # planning: view, grep, bash + lighter model
/mode sre      # incident response, infra, CI/CD, and ops work

Switch modes at any time with /mode [name] or shift+tab. The current mode is shown in the sidebar.

Treat a blocked tool as a real boundary, not a hint to route around. If the user clearly needs a denied capability, switch to the smallest suitable mode and retry the blocked action directly.

The built-in modal choreography exposes the seven modes above and starts in coordinator by default. Narrower or custom choreographies expose only states reachable through their command:mode transitions.

What each mode is for

Mode	Best for
code	General coding, edits, commands, and day-to-day development
chat	Read-only Q&A and explaining a codebase without changing files
coordinator	Delegation-first synthesis and bounded specialist orchestration without direct implementation
review	Auditing diffs, tracing logic, and doing careful analysis
debug	Reproducing failures, running commands, and using diagnostics tools
plan	Producing plans before execution, especially with staged workflow
sre	Incident response, Terraform/Kubernetes/Helm changes, CI/CD, and infrastructure triage

/mode with no argument is a read-only status query over the shared session-mode status family. It reports current mode, reachable modes, deferred mode-change posture, and the latest bounded autoselect/manual-override fact the runtime can observe. Providing a mode changes the session posture for subsequent turns.

Deprecated compatibility input

[options.session_modes.plan]
model = "claude-haiku-4-20250514"

[options.session_modes.review]
model = "claude-sonnet-4-20250514"

If you still use options.session_modes, BMO treats it as deprecated compatibility input and translates the supported fields into choreography during config normalization.

Supported translation:

Field	Compatibility behavior
model	Translated into the matching choreography state’s model
tools	Translated into the matching choreography state’s tools.allow
system_prompt	Parsed for backward compatibility, but ignored at runtime

Use Choreography directly for new configs. It is the only active runtime owner of mode behavior, model overrides, and tool-gate intent.

Choreography: a more powerful alternative

Session modes remain useful for quick interactive switching, but they are simple and stateless. For multi-phase workflows with automatic transitions, tool gates, prompt shaping, and hooks, use Choreography instead.

Related

• Session mode autoselect (eval) — shadow telemetry and rollups for prompt-aware mode proposals (optional; separate from manually picking /mode).